This invention is in the field of drive mechanisms for transfer and plate rolls and more specifically those used in flexographic printing. It is the practice to apply ink to a transfer roll in turn in contact with an adjacent rotating plate roll. The transfer roll includes an outer cylindrical surface having a plurality of cells formed thereon to hold the ink prior to transferring to a printing plate mounted on the plate roll. The outer surface of the transfer roll eventually becomes damaged through use requiring a turning or grinding down of the outside surface reducing the outside diameter of the roll causing the tangential surface speed of the transfer roll to decrease relative to the tangential surface speed of the plate roll. The net result is an ineffective transfer of ink from the tranfer roll to the plate roll due to slippage of one roll relative to the other roll. Thus, it is the practice to replate or build up the outside diameter of the transfer roll and subsequently reform the cells on the new surface formed thereon. This procedure is quite costly and time consuming in view of the time required to remove the large transfer rolls, transport the rolls to a repair facility where the recoating and regrinding is accomplished.
Effective transfer of ink or other flowable materials is accomplished between the transfer roll and plate roll when the tangential surface speeds are matched along the area of contact between the two rolls. Thus, as the ink transfer roll diameter decreases through either wear or by the regrinding step, the rotational speed of the transfer roll may be increased to match the tangential surface speed of the plate roll. Disclosed herein is an apparatus and method for matching the tangential surface speeds between the adjacent rolls eliminating the prior need for re-plating or metalizing the worn transfer roll.
It is the practice to use a blade biased against the transfer roll to remove excess ink therefrom prior to the transfer roll contacting the plate roll. As the transfer roll is decreased in diameter, the ink wiper blade will eventually not contact the transfer roll. In order to effectively use the means disclosed herein for increasing the speed of the transfer roll, the wiper blade has been mounted on an adjustable bracket allowing the operator to move the wiper blade inwardly towards the transfer roll alleviating the necessity for unmounting and remounting of the wiper blade.